path: root/drivers/target/loopback/tcm_loop.c

/*******************************************************************************
 *
 * This file contains the Linux/SCSI LLD virtual SCSI initiator driver
 * for emulated SAS initiator ports
 *
 * © Copyright 2011-2013 Datera, Inc.
 *
 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
 *
 * Author: Nicholas A. Bellinger <nab@risingtidesystems.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 ****************************************************************************/

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/configfs.h>
#include <scsi/scsi.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

#include <target/target_core_base.h>
#include <target/target_core_fabric.h>

#include "tcm_loop.h"

#define to_tcm_loop_hba(hba)	container_of(hba, struct tcm_loop_hba, dev)

static struct kmem_cache *tcm_loop_cmd_cache;

static int tcm_loop_hba_no_cnt;

static int tcm_loop_queue_status(struct se_cmd *se_cmd);

static unsigned int tcm_loop_nr_hw_queues = 1;
module_param_named(nr_hw_queues, tcm_loop_nr_hw_queues, uint, 0644);

static unsigned int tcm_loop_can_queue = 1024;
module_param_named(can_queue, tcm_loop_can_queue, uint, 0644);

static unsigned int tcm_loop_cmd_per_lun = 1024;
module_param_named(cmd_per_lun, tcm_loop_cmd_per_lun, uint, 0644);

/*
 * Called from struct target_core_fabric_ops->check_stop_free()
 */
static int tcm_loop_check_stop_free(struct se_cmd *se_cmd)
{
	return transport_generic_free_cmd(se_cmd, 0);
}

static void tcm_loop_release_cmd(struct se_cmd *se_cmd)
{
	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
				struct tcm_loop_cmd, tl_se_cmd);
	struct scsi_cmnd *sc = tl_cmd->sc;

	if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
		kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
	else
		scsi_done(sc);
}

static int tcm_loop_show_info(struct seq_file *m, struct Scsi_Host *host)
{
	seq_puts(m, "tcm_loop_proc_info()\n");
	return 0;
}

static int tcm_loop_driver_probe(struct device *);
static void tcm_loop_driver_remove(struct device *);

static struct bus_type tcm_loop_lld_bus = {
	.name			= "tcm_loop_bus",
	.probe			= tcm_loop_driver_probe,
	.remove			= tcm_loop_driver_remove,
};

static struct device_driver tcm_loop_driverfs = {
	.name			= "tcm_loop",
	.bus			= &tcm_loop_lld_bus,
};
/*
 * Used with root_device_register() in tcm_loop_alloc_core_bus() below
 */
static struct device *tcm_loop_primary;

static void tcm_loop_target_queue_cmd(struct tcm_loop_cmd *tl_cmd)
{
	struct se_cmd *se_cmd = &tl_cmd->tl_se_cmd;
	struct scsi_cmnd *sc = tl_cmd->sc;
	struct tcm_loop_nexus *tl_nexus;
	struct tcm_loop_hba *tl_hba;
	struct tcm_loop_tpg *tl_tpg;
	struct scatterlist *sgl_bidi = NULL;
	u32 sgl_bidi_count = 0, transfer_length;

	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];

	/*
	 * Ensure that this tl_tpg reference from the incoming sc->device->id
	 * has already been configured via tcm_loop_make_naa_tpg().
	 */
	if (!tl_tpg->tl_hba) {
		set_host_byte(sc, DID_NO_CONNECT);
		goto out_done;
	}
	if (tl_tpg->tl_transport_status == TCM_TRANSPORT_OFFLINE) {
		set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
		goto out_done;
	}
	tl_nexus = tl_tpg->tl_nexus;
	if (!tl_nexus) {
		scmd_printk(KERN_ERR, sc,
			    "TCM_Loop I_T Nexus does not exist\n");
		set_host_byte(sc, DID_ERROR);
		goto out_done;
	}

	transfer_length = scsi_transfer_length(sc);
	if (!scsi_prot_sg_count(sc) &&
	    scsi_get_prot_op(sc) != SCSI_PROT_NORMAL) {
		se_cmd->prot_pto = true;
		/*
		 * loopback transport doesn't support
		 * WRITE_GENERATE, READ_STRIP protection
		 * information operations, go ahead unprotected.
		 */
		transfer_length = scsi_bufflen(sc);
	}

	se_cmd->tag = tl_cmd->sc_cmd_tag;
	target_init_cmd(se_cmd, tl_nexus->se_sess, &tl_cmd->tl_sense_buf[0],
			tl_cmd->sc->device->lun,